Container for foodstuffs

ABSTRACT

A CONTAINER FOR PACKING VEGETABLES, FRUITS TOMATO AND ORANGE JUICES, AND LIKE FOODSTUFFS IN WHICH AN ADHESIVE TAPE IS ATTACHED TO THE INNER SURFACE OF THE CONTAINER BODY TO INHIBIT CORROSION IN THE CONTAINER, THE TAPE BEING MADE OF SYNTHETIC RESIN AND EMBODYING THEREWITH METALLIC TIN IN FOIL AND/OR POWDER FROM IN AN AMOUNT SUFFICIENT TO PREVENT THE FOODSTUFF CONTENTS OF THE CONTAINER FROM DISCOLORING DURING STORAGE.

July 3, 1973 YO$H|O NAGASAWA ET AL 3,743,522

CONTAINER FOR FOODSTUFFS Filed Nov. 20, 1970 United States Patent 3,743,522 CONTAINER FOR FOODSTUFFS Yoshio Nagasawa and Shunji Yano, Sagamihara, Japan, assignors to Daiwa Can Co. Ltd., Chuo-ku, Tokyo,

Filed Nov. 20, 1970, Ser. No. 91,372 Claims priority, application Japan, Nov. 27, 1969, 44/ 94,676 Int. Cl. B65B US. Cl. 99-181 R 2 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION In canning foodstuffs, the foodstuffs are degassed, sterilized and sealed in a can in such manner that the invasion or growth of toxious microorganisms in the container are prevented thus providing that the foodstuffs can be stored for long periods without hazard of oxidation.

However, other undesirable consequences attend the canning of foodstuffs. For example, in a can or container made of tin plate, the tin frequently will dissolve from the inner surface of the can under attack by the foodstuff and in such an amount to raise a problem from a view point of sanitary regulations of foodstuffs. Moreover, when the dissolution of tin is focused at a certain point, the iron material becomes exposed directly to attack by the foodstuff causing corrosion or penetration of the can material such that the can and its contents are rendered useless.

As a counter-measure to prevent the dissolution of such tin or iron material, it has heretofore been proposed to provide a can with a special material coating on the inner surface thereof so that the material of the can will not be contacted directly by the contents thereof. The internally coated can of this kind is suitable for only certain foodstuffs such as fish or meat, since such foodstuffs cause but minimal dissolution of tin. If, however, such can is used for vegetables, fruits, juices, etc., the color of the contents will turn brown because of the limited quantity of tin available for dissolution. Such undesirable result is also encountered in a can made of chemically processed steel sheet not provided with tin plating.

In an attempt to suppress discoloration of the foodstuff contents e.g. tomato juice or orange juice in an internaly coated can made of tin plate or in a can made of chemically processed steel sheet having no tin plating, it has heretofore been proposed to incorporate a source of metallic tin inside the can to provide cathodic protection for the can material per se including the tin plating. One such expedient is to apply to the' internal surface of the can a painted or coated film having the tin in a powder form incorporated therein so that the tin inside the said coating will sacrifice under attack from the contents. However, if the contents permeate the coated film and act on tin in the container tin plate with the result that tin dissolves inside the contents, a hole is made at the point where tin dissolves, and the ferrous material of the can contacts the contents with result corrosion of the can and discoloration of the contents.

Patented July 3, 1973 Another form of contents protection is that described in US. Pat. No. 3,268,344 which comprises applying a solder of pure tin to the side seam of a can body made of internally coated tin plate so that the tin of the solder is externally attached to said seam, causing the tin to permeate inside the can from the gap of the overlapped side seam by virtue of capillary phenomenon, and bringing only the tin thus permeated into contact with the contents of the can. This type of can is apparently suitable for mass production and does not injure the interior coated film of the can. However, it is extremely difficult to control the amount of tin to be permeated inside the can and commonly the dissolution of tin occurs at such rate as to be ineffective to prevent the discoloration of the contents of the can after a period of time. This type of can is not particularly satisfactory because of the high cost of production occasioned by the use of the pure tin solder rather than conventional lead solder.

Another known form of can is described in US. Pat. No. 1,958,765. This uses aluminum in place of tin as an inhibiting agent to prevent corrosion and foodstuff discoloration, blowing or inserting aluminum or an alloy thereof into the can so as to cause the contents to act upon the aluminum rather than the tin plate of the can. However, the use of a material such as aluminum in a foodstuff container preferably is avoided since the inclusion of such material in containers holding certain foodstuffs is undesirable from the standpoint of the effect the aluminum has on the foodstuff. Moreover, the blowing of aluminum material into the interior surface of the can or the insertion of such material into the gap of the seam is not suitable for container mass production. In the latter case, it is possible that microorganisms may find egress to the can through the seam.

SUMMARY OF THE INVENTION This invention relates to a can for foodstuffs such as vegetables, fruits, tomato and orange juices, and the like which is made of tin plate internally coated or of untinned but chemically processed sheet steel, the can having applied therein an adhesive tape made of synthetic resin having metallic tin embodied therewith in the form of foil and/or finely-divided powder, the tape being applied to a suitable position or positions inside the can, preferably to the side seam of the body of can with the tape in contact with the foodstuff contents, tin being embodied in the tape in an amount sufficient to prevent the discoloration of the contents thereof during storage but the quantity of tin being insuffiicent to raise the problem of food sanitation.

BRIEF DESCRIPTION OF THE DRAWING FIGS. la-lc are a series of perspective views illustrating the construction of the tape of the present invention.

FIG. 2 is a perspective view in section of one embodiment of a can provided by the present invention, the can having an adhesive tape of synthetic resin fixed to the inside of the seam of the can body.

DESCRIPTION OF THE PREFERRED EMBODIMENTS It is' not clearly known how the discoloration of the foodstuff contents of a can occurs during storage. However, it has been established that the phenomenon of discoloration occurs after packing of the contents in the can, that it occurs during a certain period of time depending upon the particular contents packed but rarely after such period of time, that tin is one of the metals capable of prohibiting the phenomenon, and the quantity of tin which should be employed to prevent the phenomenon with respect to a given foodstuif to be filled in the can. For example, in case of a can made of internally coated tin plate in which tomato juice is packed, the juice will turn brown in one to two months after packing and hermetic sealing. If, however, tin iscaused to dissolve during this period in an amount of about 25 to 50 p.p.m. based upon the net volume of the can, the above phenomenon is prevented. For orange juice, it is 30 to 45 p.p.m. Within about one month; for white asparagus, it is 50 to 75 p.p.m. within about two months; for cauliflower or green peas, it is 30 to 40 p.p.m. within about 1 /2 to 2 months; and for green asparagus, it is 25 to 50 p.p.m. Within about three months. For the aforementioned purposes the tin is incorporated in the can itself and dissolves therein.

In accordance with the present invention, the tin is incorporated either in foil or in finely divided form, in an adhesive tape made of synthetic resin. The amount of tin to be incorporated in the can is such as to prevent the discoloration phenomenon but not to cause any problem regarding food sanitation even when the Whole amount of the tin becomes dissolved. The tape thus constituted is attached in a suitable position or positions inside the can with the tape and tin embodied therein in contact with the foodstutf contents.

It is therefore an object of the present invention to provide a can or container for foodstuffs such as vegetables, fruits and especially tomato and orange juices, etc. which is made of tin plate having an internal tinless coating or of untinned but chemically processed sheet steel and which is capable of successfully preventing the undesirable discoloration of the contents after filling and sealing thereof and thereby avoiding deterioration of the quality of the contents. This object is accomplished by allowing tin to dissolve in the contents from the adhesive tape constituted as above.

Referring now to FIGS. la-lc, the structure of the adhesive tape to be used in this invention is generally shown as the reference numeral 3. In FIG. la, it has a tin foil 6 adhered to or deposited on the surface of the body 5 of the tape. In FIG. 1b, it has a finely divided or powdery tin 7 scattered throughout the body of the tape 5. In FIG. 10, it is seen that the tape has a tin foil 6 adhered to or deposited on the surface of the body 5 while also it has a finely divided or powdery tin 7 scattered throughout the body of the tape 5.

Comparing the tape in FIG. la with that in FIG. 1b, the melt-out of tin is faster in (a) than in (b) under the same conditions. Thus when the same amount of tin is to be used, the tape in (a) is suitable for a can of the type in which discoloration would proceed rapidly. As to the tape of FIG. 1c, after the tin on the surface dissolves, the tin inside the body begins to dissolve. This is thus particularly suitable for use in the case in which discoloration proceeds comparatively rapidly for the initial part of the time but slowly for the rest part of the time.

FIG. 2 shows a body of a can 1 made of internally coated tin plate, from which it is seen that an adhesive tape 3 of FIG. 1 made of synthetic resin is attached covering the side seam 2, with the seam being soldered with lead 4 as shown. The position in which the tape 3 is to be attached may be optionally selected as the case may require, but the tape should preferably be attached on the side seam of the body of the can as shown, for fine cracks due to heat on soldering are apt to occur in the coated film over the side seam. The tape 3 can be applied either to a flat plate before the body of the can is formed therefrom, or to the internal surface of the body of the can after it has been formed.

The amount of the tin to be used in this invention or to be incorporated on and/ or within the tape is such as to prevent the discoloration of the contents of the can when the .tin dissolves therein. The determinatoin of such amount is relatively easy, since the ratio of the volume of tin to be dissolved to the net volume of the can is known with respect to various types of cans.

In this invention, therefore, there remains only the predetermined amount of tin in the can, which amount is such as to prevent discoloration of the content but not to produce a contents condition inimical to consumption of the contents by a human. Accordingly, there is no fear of excessive or insuflicient dissolution. These and other advantages of the present invention will be made clear with respect to the description given below.

In case the can is used for tomato juice and made of non-coated tin plate, the phenomenon of discoloration does not occur and the taste of the content is kept good with little odor of the can, while the dissolution of the tin amounts to as much as 300 p.p.m. in a short time which gives rise to a problem of food sanitation. On the other hand, in the conventional can made of coated tin plate, the excessive dissolution of tin does not occur but the content of the can turns brown, changes its taste in about one or two months and emits undesirable odor. This defect can be overcome by causing the tin to dissolve inside the can in an amount of 25 to 50 p.p.m. based upon the inside volume of the can.

This can be successfully accomplished in this invention by providing an adhesive tape as shown in FIGS. 1 and 2, as contrasted to the conventional methods of having the tin included in the coated film of the can or applying a pure tin solder to the side seam of the cam or inserting a piece of tin into the can, which methods have proved unsatisfactory.

Evaluation of the effect of the present invention is shown in the following examples.

EXAMPLE 1 A tin foil having an area of 10 cm. was adhered to the upper surface of an adhesive tape made of synthetic resin. The volume of tin foil used was such that when all the tin dissolves, it will amount to about 40 p.p.m. based upon the whole inside volume of the can. The tape so prepared was attached to the side seam of a can made of coated tin plate. The can was filled with tomato juice and sealed. After a two-months storage, the can was opened and the volume of the tin dissolved was found to be 25 p.p.m. The color, smell and taste of the tomato juice indicated no change, which demonstrated that the phenomenon of discoloration had successfully been prohibited. It is apparent that the remaining 15 p.p.m. of tin must have remained in the tin foil. Even if all the tin dissolved, it would not exceed 40 p.p.m. in the contents and thus not be harmful to the human body.

EXAMPLE 2 In this example, the same volume of tin was applied to adhesive tape like that described in the Example 1, except that the tin was used in powder form instead of foil and distributed throughout the body of said tape, the tin having a surface area of 20 cm The tape so prepared was adhered to the inner surface of the can. The can was then filled with tomato juice and sealed as in Example 1. As contrasted to the tin incorporated into the coated film of the inner surface of the can, the tin in this case could easily dissolve and act upon the contents. The volume of the tin dissolved was 30 p.p.m. in two months after filling of the contents, and the phenomenon of discoloration was not observed.

EXAMPLE 3 A similar test was conducted except that the tin used was in the form as shown in FIG. 10 the volume of the tin foil being area 10 cm? and the powdered tin 40 p.p.m. in total.

In two months after filling of tomato juice, the amount of tin dissolved in the can was 35 p.p.m. The contents showed no change in color nor in quality.

The above examples were effected with respect to tomato juice providing the excellent results shown. As for other foodstuffs, the amount of the tin required to prevent discoloration of the contents, the area of the tin foil, if used, to give the predetermined amount of tin inside the can and other necessary data are all known so that it is possible to easily make the adhesive tape of synthetic resin and provide it with the amount of tin required for the particular kind of canned foodstuffs.

It is to be understood that the feature of the invention lies in provision of an adhesive tape as described above to be attached inside the can as a means of providing a required amount of tin therein.

The adhesive tape used in this invention is, as set forth above, provided with the tin in powdery or foil form, the volume of which is predetermined such as to prevent discoloration of the contents when the tin dissolves, which tape optionally can be attached to a suitable position or positions on the inner surface of the can and in contact with the contents.

What is claimed is:

1. In a can for packing foodstuffs including tomato juice and orange juice and the like which includes a can body of tin plate having a tinless coating on the internal surface thereof, an adhesive tape made of synthetic resin attached to the internal surface of said can, said adhesive tape embodying metallic tin in an amount suflicient to prevent discoloration of the foodstuff during storage after packing in said can but insuflicient to render the contents dangerous for human consumption, the tin being embodied in said tape as a foil of tin adhered to a face of said tape, and further as tin distributed in a finely divided form throughout the body of said tape, the tape being disposed in said can and the finally dissolved tin distributed in said tape such that both said foil and finely dissolved tin are in contact with said foodstuff.

2. In a can for packing foodstuffs including tomato juice and orange juice and the like which includes a can body of untinned but chemically processed sheet steel, an adhesive tape made of synthetic resin attached to the internal surface of said can and in contact with the foodstuff, said adhesive tape embodying metallic tin in an amount sufiicient to prevent discoloration of the foodstuff during storage after packing in said can but insuflicient to render the contents dangerous for human consumption, the tin being embodied in said tape as a foil 0 of tin adhered to a face of said tape, and further as tin distributed in a finely divided form throughout the body of said tape, the tape being disposed in said can and the finely dissolved tin distributed in said tape such that both said foil and finely dissolved tin are in contact with said foodstuff.

References Cited UNITED STATES PATENTS 2,934,236 4/1960 Groves 22063 R X 1,811,160 6/1931 Stevenson '99 1s1c 1,958,765 5/1934 Perkins 99-181 R X 2,055,507 9/1936 Shirley. 3,134,682 5/1964 Vogel et al 99-181 R 2,245,561 6/1941 Nelson et a1 220-64 3,268,344 8/1966 Kamm 99-181 R 3,475,260 10/1969 Stokes 22063 R X 2,797,843 7/1957 Oruns 22063 R 1,867,637 7/1932 Warth.

3O TIM R. MILES, Primary Examiner S. L. WEINSTEIN, Assistant Examiner 

